Clinical research, including case studies of unusual conditions, are conducted on a variety of subjects related to the oral cavity and oral health. Methods utilized include chart and literature reviews and clinical evaluation of various therapeutic regimens. A recent case study documented the oral complications in a patient with Erdheim-Chester disease. The patient lost all teeth due to rapidly progressing periodontal disease related to fatty infiltration of bone marrow tissue associated with E-C. Endosseous dental implants were utilized to replace lost mandibular teeth. Despite the abnormal bone marrow tissue present in the E-C patient, the implants appear to be functioning successfully to support a fixed bridge. Another case study documented the transformation of a long standing oral lichen planus of the dorsal surface of the tongue to squamous cell carcinoma. Evaluation of various therapeutic regimens have included (1) use of a dentin bonding agent and a composite resin to restore posterior teeth, (2) a collaborative study with the Upjohn Company evaluating the use of a non-steroidal anti-inflammatory agent in the treatment of periodontitis, and (3) the surgical treatment of jaw immobilization associated with fibrodysplasia ossificans progressive. Chart reviews and clinical examinations were used to document oral conditions associated with anorexia and bulimia nervosa.